B30. Tropical Cyclones in the high-resolution E3SM

Title

Tropical Cyclone activity in the high resolution E3SM v1

Authors

Karthik Balaguru, PNNL

Abstract

Here we present an overview of simulated Tropical Cyclones (TCs) in the high and low resolution versions of the fully coupled Energy Exascale Earth System Model (E3SM) v1. In the high resolution version of the model, the simulation of TCs is reasonable when compared to observations. An average of 65 TCs are simulated globally per year, which is lower than the observed value of around 90. Also, the TC intensity distribution in various basins is in reasonable agreement with observations, except that the model slightly under produces major TCs and over produces weaker TCs. An analysis of the Genesis Potential Index, based on thermodynamic Potential Intensity and Vertical Wind Shear, is performed to understand the relative distribution of TC production in different basins with respect to observations. On the other hand at low resolution, only 15 TC-like vortices are simulated globally. Despite the bias, this value is comparable to the CMIP5 multi-model mean, where spatial resolution is also around 1 degree. Further, in the low-resolution version, E3SM relatively underproduces TC-like vortices in the Atlantic basin, behavior that is consistent with many CMIP5 models and is possibly related to biases in the simulation of African Easterly Waves at that resolution.